Field of the Invention
The present invention relates to a method and a system for propagating a scaling mode in a production process controlled and executed by a manufacturing executing system (MES).
As it is well known, a method for manufacturing processes planned by an enterprise resource planning (ERP) and produced by a shop floor, provides a manufacturing executing system (MES) for modeling, planning, scheduling and implementing the manufacturing processes and controlling the corresponding production steps at the plant floor level.
In particular, the enterprise resource planning (ERP) is a system including hardware devices and corresponding software applications for planning the business resources of an enterprise, i.e. material provisions, human resource managements, purchasing, orders, profits, finance, inventory controls, customer managements, etceteras, while the term “shop floor” has been used to indicate a system supporting the control of single machines performing production actions and being involved in the manufacturing processes, for example by measuring the number of pieces produced per hour by each machine or the functioning parameters thereof, the quality of the pieces produced and so on.
MES is an intermediate layer providing computing machines and software tools between the ERP upper layer and the shop floor lower layer, including a software tool for production order management, which receives requests of production from the ERP, and a software tool for production modeling, which supports the phases of selecting and managing the resources to be involved in the manufacturing processes, i.e. employees, machines and materials, in order to realize a planned manufacturing process within required time constrains.
Therefore, manufacturing execution systems being regulated by the ANSI/ISA/95 standard require modeling plant equipment for both scheduling and controlling activities. Therefore, the productive process typically consists of a production request which defines a request for production for a single product. The predefined product is identified by a production rule, each of which is divided in many segment requirements that represent simple productive actions which are controlled by the manufacturing execution system.
Thus, a production request contains at least one segment requirement; even it spans all production of the product. A segment requirement contains at least one material produced requirement with the identification, the quantity and the units of measure of the product to be produced. Usually, in MES systems, the user would like to modify the quantity of the product to be produced due to various reasons, such as machine down time, shortage of materials, and absence of personnel. Of course, it would be desirable that the MES system contains a mechanism able to modify all the quantity of the resources involved (e.g. material in input, personnel, equipment) by rescaling the resources involved.
For example, suppose an initial production request of 1,000 kg tomato sauce will require 1,400 kg of tomatoes, 100 kg of Basil and 20 kg of salt and other spices. The user plans this production request and after start of the execution of this production process a shortage of tomatoes shows up, for example only 700 kg of tomatoes are available due to the failure of a new delivery in time. Now, the user has to update the initial production request from 1,000 kg tomato sauce to 500 kg tomato sauce which will now require to change all the other resources involved such as 700 kg tomatoes, 50 kg Basil and 10 kg of salt and other spices. Further, also some equipment can be made re-available for other production requests since for example the cooking station is only used for 30 min instead of 60 minutes. Sometimes the simple linear rescaling as given in this example does not reflect the true situation on the resources involved and a more complex calculation needs to be performed.
Up to now, a modification or an update of the quantity of resources required to produce a product at an updated quantity in a MES can be carried out calling a set of user interface method. The formula used to modify the quantities of the different resources which are involved in the production request will be stored inside the MES system who should apply this formula with a call to a user interface method. In complex MES systems, different formulas should be stored and must be applied depending on the proper situation. This approach leads to the MES system having a collection of formulas to be applied at different levels. Each resource requiring an update of the quantities will be involved in calling the user interface method with the proper formula. The result of this approach produces correct results but when the production process controlled by the MES system involves all the complexity possible, the performance of the entire system has to be decreased due to the user interface method.